The industry of surfactants and synthetic detergents dates back to the 1930s. Synthetic surfactants and detergents derived from petrochemical raw materials have broken the dominance of soaps, and the current research interests of surfactants are alkyl epoxy carboxylates (AEC), gemini surfactants, AB type block polymer surfactants, bola type surfactants, dendrimer type surfactants, low foaming or foamless surfactants. With the continuous improvement of the people's living standards and environmental awareness, the traditional commercial surfactant has been unable to meet the requirements of surfactant safety, environmental protection and low cost, and it is being gradually eliminated, replaced by a new type of green surfactant. So green surfactants such as gemini surfactants have been favored by scientists around the world and have set off a new research boom.
Gemini surfactants comprises two or more of the same or almost identical surfactant monomers connected by chemical bonds where the amphiphilic components are linked together via the hydrophilic head groups or near the hydrophilic head groups. These surfactants include anionic, nonionic, cationic, zwitterionic, anionic-nonionic and cationic-nonionic types. The special structures of gemini surfactants determine that they have better performance than conventional surfactants. Usually, they have two hydrophilic groups and hydrophobic groups connected through the linking chain. The connection by a chemical bond reduces the electrostatic repulsion between the polar groups and the force between the hydration layers, and so endows the gemini surfactant extremely low cmc (critical micelle concentration). At the same time, due to the compact symmetrical structure the gemini surfactant molecules have special self-assembly behavior and excellent ability to reduce the surface tension of the aqueous solution, so that they are widely used in detergents and cosmetics industries, the fields of petroleum, coal, mining, textile, medicine and other industries and agriculture.
The patent literature (Application Serial No: CN201010532886.6) discloses a gemini surfactant and a process for the preparation thereof. The structure of the gemini surfactant is shown in formula (I).

Wherein: R is selected from the group consisting of C8-C16 alkyl; n is a natural number from 1 to 3, and a process for the preparation of a cationic gemini surfactant represented by the formula (I) in the literature, comprising the steps of: 1) C8-C16 fatty alcohols and epichlorohydrin are reacted in the presence of a basic compound and a phase transfer catalyst to form a compound of the formula (II) wherein R is as defined in formula (I); 2) the compound represented by the formula (II) and the polyethylene glycol are reacted in the presence of an alkali metal and are acidified to give a compound of the formula (III), wherein the degree of polymerization of the polyethylene glycol is from 1 to 3; 3) the compound represented by the formula (III) is reacted with chlorosulfonic acid and is alkalized to give a gemini surfactant represented by the formula (I). The surfactants provided by the above documents have good temperature resistance, salt resistance, foaming property, emulsifying property and good synergistic effect with other types of surfactants. However, the instability, strong volatility and potential carcinogenic toxicity of epichlorohydrin results in high preparative cost of the above-mentioned gemini surfactants and limits their further industrialization produce.
Highly active dodecyl and tetradecyl glucose gemini surfactants (Patent Publication No. CN102895914A; Patent Publication No. CN102895915A) have been developed in our lab. Further improvement of the surface activity through combination with other surfactants is an effective way to optimize surface activity, which can greatly reduce the cost of research and industrial application.